The nuclear engineer in charge at Japan’s Fukushima Daiichi power plant during the worst nuclear disaster since Chernobyl has died of cancer at the age of 58.

Masao Yoshida, who was head of the Japanese nuclear power plant at the time of the 2011 tsunami, has died of esophageal cancer. The illness was not believed to be a result of radiation exposure, although this cannot be ruled out with any certainty.

Yoshida had been chief manager at Fukushima Daiichi for 9 months when the site was engulfed by a 42-foot wave, leading to fuel meltdowns in three reactors and the release of radiation into the environment.

Whilst the owners of the plant, Tokyo Electric Power, were criticized for the handling of the events, Yoshida received praise for his efforts to handle an attempt to pump in seawater to cool the reactors. However, Yoshida was criticized for not installing adequate measures against a tsunami while he headed up Tepco's nuclear facility management division, before the disaster.